title: K0.78Na0.22MoO2AsO4.
abstract: The title compound, potassium sodium dioxidomolybden-um(VI) arsenate, K0.78Na0.22MoO2AsO4, was synthesized by a solid-state reaction route. The structure is built up from corner-sharing MoO6 octa-hedra and AsO4 tetra-hedra, creating infinite [MoAsO8]∞ chains running along the b-axis direction. As, Mo and all but one O atom are on special positions (4c) with m symmetry and K (occupancy 0.78) is on a position (4a) of -1 in the tunnels. The possible motion of the alkali cations has been investigated by means of the bond-valance sum (BVS) model. The simulation shows that the Na(+) motion appears to be easier mainly along the b-axis direction. Structural relationships between the different compounds of the AMoO2AsO4 (A = Ag, Li, Na, K, Rb) series and MXO8 (M = V; X = P, As) chains are discussed.
authors.affiliation: Laboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 ElManar II Tunis, Tunisia.
authors.forename: Raja
authors.initials: R
authors.lastname: Jouini
authors.forename: Chahira
authors.initials: C
authors.lastname: Bouzidi
authors.forename: Mohamed Faouzi
authors.initials: MF
authors.lastname: Zid
authors.forename: Ahmed
authors.initials: A
authors.lastname: Driss